If you like to handle your music and photos with iTunes and iPhoto, Webbla is the right application to handle your bookmarks.

Webbla is a modern bookmark manager for Mac OS X Leopard that helps you in organizing your bookmarks visually. It also offers you an easy way to keep track of website updates.
Instead of remembering your bookmarks by title, Webbla gives you a new way to remember them visually. Personalizing your bookmarks with tags or keeping them in different categories will help you to come back to them easily.

Browser compatibility
Define your own shortcuts to add bookmarks from your web browser to Webbla.
Customizable web browser scripts make it easy to open bookmarks in different ways with all applications supporting AppleScript.
Over standard html bookmark files you can import and export your bookmarks to and from Camino, Firefox, OmniWeb, Opera, Safari and more.

Mac OS X System integration
Webbla support Spotlight, Cover Flow and Quick Look, so you can easily find and preview your bookmarks with the Finder.

probably good for beginners but fails to be effective in massive bookmarking. right now i'm importing 7000 bookmarks with tags+notes
webbla crashed at 4000. restart, crash at 6200. more than 6 hours have passed and we're not there yet

tag scrolling is ineffective with 2000+ tags

what is webbla for if not for massive bookmarking?
if you do less, go with shovebox. if you do more, try webnote